From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: Xen Benchmarking guidelines Date: Tue, 14 Aug 2007 11:53:36 +0100 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Nick L. Petroni Jr." , xen-devel@lists.xensource.com Cc: Michael Hicks List-Id: xen-devel@lists.xenproject.org On 14/8/07 11:37, "Nick L. Petroni Jr." wrote: > In general, I'm using standard benchmarking best practices, i.e., > disabling unnecessary services in host and guest, etc. Perhaps this is > related to VCPU scheduling? Should I try pinning a vcpu? Please let > me know if I can provide more details. Any help or insight would be much > appreciated! It should be possible, and in fact difficult not, to get almost native scores on SPECINT benchmarks from within an HVM guest. There's no I/O or system activity at all -- it's just measuring raw CPU speed. The most likely culprits are scheduling problems or time problems in the HVM guest. To discount scheduling issues, it's probably worth pinning your HVM VCPU to a single physical CPU (and set the affinity of dom0 so that it *doesn't* run on that physical CPU) and see if that helps. For time issues, you can time your SPECINT runs with a stopwatch. Or perhaps you can come with some more automatable means, but you should aim to take before/after timestamps from *outside* the HVM guest, since you're trying to ascertain whether the HVM timekeeping is screwed on your system. -- Keir